Many-body Hilbert space scarring on a superconducting processor

Quantum many-body scarring (QMBS) is a recently discovered form of weak ergodicity breaking in strongly interacting quantum systems, which presents opportunities for mitigating thermalization-induced decoherence in quantum information processing applications. However, the existing experimental realizations of QMBS are based on systems with specific kinetic constrains. Here we experimentally realize a distinct kind of QMBS by approximately decoupling a part of the many-body Hilbert space in the computational basis. Utilizing a programmable superconducting processor with 30 qubits and tunable couplings, we realize Hilbert space scarring in a non-constrained model in different geometries, including a linear chain and quasi-one-dimensional comb geometry. By reconstructing the full quantum state through quantum state tomography on four-qubit subsystems, we provide strong evidence for QMBS states by measuring qubit population dynamics, quantum fidelity and entanglement entropy after a quench from initial unentangled states. Our experimental findings broaden the realm of scarring mechanisms and identify correlations in QMBS states for quantum technology applications.